i need help. i have a 1973 Harley Davidson y-440 sled with a tilletson carb. i had carb rebuilt, and sled will not run on its own, but will run if i shoot starting fluid in carb or shoot in gas. i put in new fuel and new fuel lines and rebuilt carb. cant figure it out.

 

Does gas come out of the fuel line when it's disconnected from the carb?

 

Looked inside the gas tank for a filter and replaced it?
Let me guess it's a Harley Davidson AMF machine?
Do not waste a whole lot of time any money on this machine, it was a top heavy poor design even when it was new.

 

Since the engine runs when you manually feed it fuel you have a fuel problem. Start at the beginning and follow the fuel system. Can fuel leave tank and make it to the pump? Is the pump working? Does fuel make it to the carburetor? If the fuel is making it to the carb you likely have a carburetor problem.

 

the carb is a tillotson. it has a diaprahm in the carb which is the fuel pump. have fuel to carb. carb was cleaned out and rebuilt. tried a different carb, same model and still has same problem

 

If the engine runs when you squirt fuel in the throat of the carburetor it still points to a fuel/carburetor problem. Are you certain the other carburetor you tested was good? Is fuel making it to the carburetor?

 

yes it is. fuel is to the carb

 

If the fuel is getting to the carb, the next thing to check is the float level. That can be done by removing the top from the carb & blowing air through the fuel line. Wen the float is below level, the air should flow uninterrupted. When the float is lifted to the level position, that's when the air should stop.

 

Tillotson carburetors are pulse type and do not have a bowl or float. I still think his carburetor is not working.

 

Even if the carbs were cleaned and rebuilt that does not mean they are functional. I have spent weeks on carbs and still failed to clean out certain ports. If gas and oil dry up enough they can become strong like solder.

One option is to put an air compressor to different ports in the carbs, if there is gas in them and there is flow it will blow out everywhere. If not there is a clog somewhere. If there is a clog the best thing you can do is remove the carbs and then strip them of any rubber / plastics and then boil them in water. Does not need to be a hot boil but rather just barely a boil. This will cause everything to pop free, like stuck in stuff, and this method can also free up seized carbs because the temperature and pressure of boiling causes the rust to break free.

If the ports are not clogged then your issue may be a seal or gasket, so there is air pulling in which would make it hard for the carbs to pull gas from the tank.